In the field of communications, the same base station may have antennas of a plurality of communications systems. Due to restriction to geological locations, distances among some antennas are very small, leading to isolation reduction among antennas, giving a plurality of wireless signals a chance to simultaneously enter into a receiver, thus causing severe interferences to available signals. Therefore, improving isolations among antennas from different systems to enhance anti-interference capabilities has significantly crucial meanings to the communications system.
In communication systems, because of close distances among antennas and poor isolation, interferences exist among different base station systems. Hitherto there are mainly two solutions provided. One is to increase isolations among antennas by changing heights, distances and pitch angles of the antennas. Being restricted to the size of the space, degrees of difficulty for the construction and requirements for the coverage, the method is limited in terms of improvement. Another method is to improve the anti-interference of the technical index in the antenna design. This method is to change the design at the module phase and has difficulty in realization of antennas, thus being not suitable for the base station's antennas in network use.
Chinese patent (CN201010276357) describes an anti-interference wide-beam WLAN base station antenna, including a metal reflector, a microstrip plate fixed on the metal reflector through an insulating shore, and a radiate array antenna laid on the microstrip plate. The radiate array antenna includes a set of microstrip transmission lines laid on the back of the microstrip plate and a plurality of radiation units laid on the front of the microstrip plate and arranged in columns. The antenna involves a simple manufacture technology, has a light structure, needs a low cost, and is easy to be put into large-scale industrial production and broadened in the aspect of beam-width in the horizontal plane, as well as solves the interference problem between the same polarization when current available antennas of a vertically polarized kind are used in practice. The patent increases anti-interference to the design of the antenna per se, mainly aiming at the interference problem the same polarization of antennas of vertically polarized kind.
According to the Chinese patent (CN2399833), it discloses an apparatus for absorbing and shielding electromagnetic waves of a mobile phone antenna, including a half-shielding apparatus on an antenna body, wherein the apparatus mainly includes at least one small absorbing slice and a spacer which can efficiently shield electromagnetic waves directed to a user. An inner diameter of the spacer is not greater than an outer diameter of the antenna. The spacer is a metal slice or an absorbing material. The absorbing slice is connected to or embedded in the spacer. Outside the spacer there is a housing. The implementation process of the patent impacts a radiation pattern. The cell phone antenna is an omni-directional antenna. By shielding radiation signals radiated to a brain direction, the patent mostly lowers a detriment to a human body from the electromagnetic waves. The patent has greatly changed a main beam pattern per se, thus not being suitable to handle interferences among antennas of multiple base stations.